Originally Posted by
Doge
I avoided dealing with moving weight from derailleur to frame because I agree. Apparently we both understand the effects of mass and its location.
My "thesis" was that generally more expensive components are better - and you generally get value for $500 - in that mid-range. I buy lots of stuff that is more expensive, lighter and "not better", but I am not like the OP. In the mid-range Ultegra and the parts that come with it are better than 105 and parts that come with it - that's all.
I don't argue with that - I take issue with what you originally wrote: "
the originally lighter bike (with added weights - ed) would be faster and ride better. The lighter stock bikes tend to have more refined components that remove weight where it is less needed. "
That's saying that the lighter bike, because of the higher quality group set etc, would be faster and ride better. This is a fairly provocative statement, and a dubious one in my opinion. These higher quality components will not make your bike faster nor handle better. And riding better because of removing the weight "from where it is less needed" remains also unsupported, and in my opinion also dubious. Unless you're talking about thinning tube walls in areas less stressed, but that isn't what I call a "component".
OP asked specifically for performance gains from buying a lighter bike. In a nutshell, all he can honestly expect is the weight difference over total weight, up a steep enough hill. Roughly 1%-2%. Do you honestly believe that the slightly higher tier of components on a $500 more expensive bike will produce more performance gains for OP than, for example, $500 of quality racing tires and a better wheelset?
Originally Posted by
Doge
The 2nd point was depending on riding style/type - a rider may feel this difference. A 10,000mile/year rider would more times than not be able to tell you which bike was the $500 more costly.
I have put numbers to this stuff in the past (general physics in the 80s when I commuted to school by bike) and it is hard. I find tests matter more than calculations because no calculation I read account for the side to side movements and those vary a whole bunch rider to rider. I support my kid who is a 10K mile/year guy and I know he notices this stuff. Our recent and ongoing test - wheel weight and aero (see 33 Tech forum).
Let's not get into qualifications about riding or education, since I think those are meaningless in internet discussions. I ride a lot also and I know the science, which claim makes me no more nor less likely to know what I'm talking about.